An electron (mass $9 \times 10^{-31}\text{ kg}$ and charge $1.6 \times 10^{-19}\text{ C}$) is moving in a circle with a speed of $3.2 \times 10^7\text{ m/s}$ in a magnetic field of $4.5 \times 10^{-4}\text{ T}$ perpendicular to it. Calculate : (i) the radius of the circular path, (ii) its frequency of rotation, and (iii) its energy.